We study the dependence of magnetic and magnetotransport properties of NiFe/Cu/Co pseudo spin-valves on the pressure of the Ar sputtering gas during magnetron deposition. The giant magnetoresistance (GMR) ratio as a function of the sputtering pressure behaves non-monotonic with a maximum of about 4% at an intermediate pressure of 0.87 x 10-2 mbar. Atomic force microscopy image reveal a variation of the grain structure with increasing sputtering pressure: The grain size first decreases and then the grains start clustering for highest pressures. These changes influence the spin-independent scattering and thus the GMR ratio via the saturation resistance R_s.